Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry LaboratoryKristen L. Cacciatore, Jose Amado, Jason J. Evans, and Hannah SevianPresents a novel first-year chemistry experiment that asks students to replicate procedures described in sample lab reports that lack essential information. This structure is designed to promote students' experimental design and data analysis skills as well as their understanding of the importance and essential qualities of written and verbal communication between scientists.Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah. J. Chem. Educ.2008, 85, 251.

Equilibrium |

Green Chemistry |

Periodicity / Periodic Table |

Solutions / Solvents |

Stoichiometry |

Titration / Volumetric Analysis

A Simplified Model To Predict the Effect of Increasing Atmospheric CO2 on Carbonate Chemistry in the OceanBrian J. Bozlee, Maria Janebo, and Ginger JahnThe chemistry of dissolved inorganic carbon in seawater is reviewed and used to predict the potential effect of rising levels of carbon dioxide in the atmosphere. It is found that calcium carbonate may become unsaturated in cold surface seawater by the year 2100, resulting in the destruction of calcifying organisms such as coral.Bozlee, Brian J.; Janebo, Maria; Jahn, Ginger. J. Chem. Educ.2008, 85, 213.

Applications of Chemistry |

Aqueous Solution Chemistry |

Atmospheric Chemistry |

Equilibrium |

Green Chemistry |

Water / Water Chemistry

Using the Science Writing Heuristic To Improve Students' Understanding of General EquilibriumJames A. Rudd, II, Thomas J. Greenbowe, and Brian M. HandThis study examines the performance of students using the Science Writing Heuristic approach, which facilitates scientific inquiry by structuring the laboratory notebook in a format that guides students to answer directed questions, on lecture exams and a laboratory practical exam on chemical equilibrium.Rudd, James A., II; Greenbowe, Thomas J.; Hand, Brian M. J. Chem. Educ.2007, 84, 2007.

Equilibrium |

Learning Theories |

TA Training / Orientation |

Student-Centered Learning

The Use of Limits in an Advanced Placement Chemistry CoursePaul S. Matsumoto, Jonathan Ring, and Jia Li (Lily) ZhuThis article describes the use of limits in topics usually covered in advanced placement or first-year college chemistry. This approach supplements the interpretation of the graph of an equation since it is usually easier to evaluate the limit of a function than to generate its graph.Matsumoto, Paul S.; Ring, Jonathan; Zhu, Jia Li (Lily). J. Chem. Educ.2007, 84, 1655.

Equilibrium Constants and Water Activity RevisitedDavid KeeportsSubtle arguments based upon the use of chemical potentials show that numerical values of solute molar concentrations can be used as good approximate activities in equilibrium calculations for reactions involving dilute solutions.Keeports, David. J. Chem. Educ.2006, 83, 1290.

Equilibria That Shift Left upon Addition of More ReactantJeffrey E. LacyMost textbook presentations of Le Chtelier's principle in general and physical chemistry do not include a discussion of constant pressure conditions for which addition of a reactant can shift the equilibrium to the left. We propose presentations of isothermal, open systems at constant pressure for both levels of study by using concepts and skills that the respective students already possess. In addition, we derive novel criteria based on the stoichiometry of the reaction that can be used to identify those equilibria that will shift left upon addition of more reactant. Lacy, Jeffrey E. J. Chem. Educ.2005, 82, 1192.

Equilibrium |

Mathematics / Symbolic Mathematics |

Thermodynamics

Equilibrium Constants and Water ActivityDavid KeeportsGeneral chemistry instructors are faced with a dilemma when introducing the topic of equilibrium constants: These constants are correctly written in terms of activities, yet activity is a complex topic better treated rigorously in a physical chemistry course than superficially in a general chemistry course. Thus, to introduce equilibrium calculations, it is necessary to use approximate forms for equilibrium constants. However, I find that some commonly used textbooks provide incorrect arguments leading to approximate equilibrium constants for aqueous reactions.Keeports, David. J. Chem. Educ.2005, 82, 999.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Water / Water Chemistry

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoThe traditional method to determine the equilibrium concentration of chemicals in a reaction, given the equilibrium constant and the initial concentration of chemicals in the reaction, involves the determination of the reaction quotient. This article will demonstrate that this step may be eliminated; thereby simplifying the algorithm to solve such problems. Such a reduction in the complexity of the algorithm may result in more students successfully being able to solve such problems. Matsumoto, Paul S. J. Chem. Educ.2005, 82, 406.

Equilibrium |

Learning Theories |

Chemometrics

Unified Approximations: A New Approach for Monoprotic Weak Acid–Base EquilibriaHarry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. TesfaiThis article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero. Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ.2004, 81, 1367.

Acids / Bases |

Equilibrium |

Chemometrics

Playing-Card EquilibriumRobert M. HansonA simple hands-on simulation suitable for either classroom use or laboratory investigation involves using a standard deck of playing cards to explore the statistical aspects of equilibrium. Concepts that can be easily demonstrated include fluctuation around a most probable distribution, Le Chtelier's principle, the equilibrium constant, prediction of the equilibrium constant based on probability, and the effect of sample size on equilibrium fluctuations. Hanson, Robert M. J. Chem. Educ.2003, 80, 1271.

The Relative Acidities of Water and MethanolHenry I. AbrashAnalysis of the disparity between the way the acidity constant of water is presented in general chemistry and organic chemistry textbooks.Abrash, Henry I. J. Chem. Educ.2001, 78, 1496.

Acids / Bases |

Equilibrium

The State of Division of Solids and Chemical EquilibriaJoão C. M. Paiva and Victor M. S. GilAn experiment and a computer simulation are presented to address a counterintuitive situation often encountered when teaching chemical equilibria. This is prompted by the question "How can the subdivision of a solid reactant affect the reaction rate and not the composition of the equilibrium state?" Paiva, João C. M.; Gil, Victor M. S. J. Chem. Educ.2001, 78, 222.

Are We Taking Symbolic Language for Granted? Paul Marais and Faan JordaanThis study formed part of a broader investigation into the role of language in teaching and learning chemical equilibrium. Students were tested for their understanding of 25 words and five symbols commonly used in connection with chemical equilibrium. This test showed that most of the students had an inadequate grasp of the meaning of all five symbols. It also showed that, on the average, their understanding of symbols was more problematic than their understanding of words.Marais, Paul; Jordaan, Faan. J. Chem. Educ.2000, 77, 1355.

Simulating Dynamic Equilibria: A Class ExperimentJohn A. Harrison and Paul D. BuckleyA first-order reversible reaction is simulated on an overhead projector using small coins or discs. Results illustrate how dynamic equilibria are established and allow the introduction of the concept of an equilibrium constant. Le Chtelier's principle is illustrated by further simulations. Harrison, John A.; Buckley, Paul D. J. Chem. Educ.2000, 77, 1013.

Equilibrium |

Rate Law |

Reactions

Simulations for Teaching Chemical EquilibriumPenelope A. Huddle, Margaret Dawn White, and Fiona RogersThis paper outlines a systematic approach to teaching chemical equilibrium using simulation experiments that address most known alternate conceptions in the topic. Graphs drawn using the data from the simulations are identical to those obtained using real experimental data for reactions that go to equilibrium. This allows easy mapping of the analogy to the target. Huddle, Penelope Ann; White, Margaret Dawn; Rogers, Fiona. J. Chem. Educ.2000, 77, 920.

Equilibrium |

Learning Theories

An Acid-Base Chemistry Example: Conversion of NicotineJohn H. SummerfieldThe current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry.Summerfield, John H. J. Chem. Educ.1999, 76, 1397.

Graphing Calculator Strategies for Solving Chemical Equilibrium ProblemsHenry Donato Jr.A general method for finding the roots of polynomial equations using the ubiquitous and inexpensive graphing calculator is presented. It is suggested that important reactions, which are not discussed in introductory chemistry courses because of computational considerations, may now be discussed. Donato, Henry, Jr. J. Chem. Educ.1999, 76, 632.

Aqueous Solution Chemistry |

Learning Theories |

Equilibrium

The Complexity of Teaching and Learning Chemical EquilibriumLouise Tyson, David F. Treagust, and Robert B. BucatThis paper discusses three key issues relevant to secondary school chemistry teaching. They arise from a study of students' understanding of chemical equilibrium using qualitative and quantitative research methods. Tyson, Louise; Treagust, David F.; Bucat, Robert B. J. Chem. Educ.1999, 76, 554.

Equilibrium |

Learning Theories

Equilibrium Principles: A Game for StudentsLionel J. Edmonson Jr. and Don L. LewisThe laboratory exercise is a game using marked sugar cubes as dice. The game emphasizes the dynamic character of equilibrium. Forward and reverse rate-constant values are used to calculate an equilibrium constant and to predict equilibrium populations. Predicted equilibrium populations are compared with experimental results.Edmonson, Lionel J., Jr.; Lewis, Don L. J. Chem. Educ.1999, 76, 502.

The Fizz Keeper, a Case Study in Chemical Education, Equilibrium, and KineticsReed HowaldThe chemistry of the loss of carbonation from carbonated beverages on storage is considered. Increasing the pressure of CO2(g) will restore carbonation, but an increase in pressure adding air should not affect the equilibria. It can and does, however, affect the kinetics-the rate at which a new equilibrium is established. Thus the Fizz Keeper is effective for storage of resealed pop containers for hours, but not for periods of weeks or months. Howald, Reed. J. Chem. Educ.1999, 76, 208.

Transport Properties |

Equilibrium |

Gases |

Kinetics |

Aqueous Solution Chemistry |

Consumer Chemistry |

Applications of Chemistry

Equilibrium: A Teaching/Learning ActivityAudrey H. WilsonThis article describes hands-on activities for high-school or undergraduate students designed to clarify important concepts involved in early studies of equilibrium. Concepts included are that at equilibrium, rate of forward reaction = rate of backward reaction; concentrations of both reactants and products remain constant; the equilibrium constant is constant at the same temperature but changes as the temperature changes; and equilibrium may be approached from different starting points. Wilson, Audrey H. J. Chem. Educ.1998, 75, 1176.

Equilibrium

"Conceptual Questions" on LeChatelier's PrincipleBenjamin P. HuddleThree "conceptual questions" presented are designed to assess the student's ability to conceptualize chemical equilibrium and to predict the effect of changes made to a system at equilibrium, using LeChatelier's principle, without doing any equilibrium constant calculations.Huddle, Benjamin P. J. Chem. Educ.1998, 75, 1175.

Equilibrium

Formation and Dimerization of NO2 A General Chemistry ExperimentApril D. Hennis, C. Scott Highberger, and Serge Schreiner*A general chemistry experiment which illustrates Gay-Lussac's law of combining volumes. Students are able to determine the partial pressures and equilibrium constant for the formation and dimerization of NO2. The experiment readily provides students with data that can be manipulated with a common spreadsheet. Hennis, April D.; Highberger, C. Scott; Schreiner, Serge. J. Chem. Educ.1997, 74, 1340.

Gases |

Equilibrium |

Quantitative Analysis |

Stoichiometry

Why and How To Teach Acid-Base Reactions without EquilibriumTerry S. CarltonA stepwise method enables students to predict which acid-base reactions occur when two solutions are mixed. The complexities of equilibrium are avoided by treating reactions as all-or-none and by providing a table of acids in order of strength. Carlton, Terry S. J. Chem. Educ.1997, 74, 939.

Learning Theories |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Ionization or Dissociation?Emeric SchultzThe use of the terms Dissociation and Ionization in the teaching of chemistry is discussed. It is suggested that the term dissociation, and what it suggests in terms of ordinary language, is inappropriate when used in certain contexts. Since an alternate and more physically correct term, specifically ionization, is available for these contexts, it is argued that this term be used consistently in these contexts.Schultz, Emeric. J. Chem. Educ.1997, 74, 868.

Equilibrium |

Nomenclature / Units / Symbols

Thermodynamics and SpontaneityRaymond S. OchsDespite the importance of thermodynamics as the foundation of chemistry, most students emerge from introductory courses with only a dim understanding of this subject. Ochs, Raymond S. J. Chem. Educ.1996, 73, 952.

Equilibrium CalculatorAllendoerfer, RobertThe equilibrium calculator can calculate the equilibrium concentrations of all reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 126.

The acid equilibrium constant is unity!Baldwin, W. G.; Burchill, C. E.The attempt to assign a non-unity value to this equilibrium constant is a consequence of misunderstanding the way in which the (nearly) constant concentration or activity of the solvent in a dilute solution (or of a pure solid or liquid in a heterogeneous system) is treated when formulating the conventional equilibrium constant expression.Baldwin, W. G.; Burchill, C. E. J. Chem. Educ.1992, 69, 514.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

Chemical equilibrium: I. The thermodynamic equilibrium constantGordus, Adon A.This is the first article in a series of eight that investigates the various assumptions that result in the simplified equilibrium equations found in most introductory texts. In this first article, the author considers the general nature of the constant K, Le Chatelier's principle, and the effect of the temperature on K.Gordus, Adon A. J. Chem. Educ.1991, 68, 138.

Computer simulation of chemical equilibriumCullen, John F., Jr.108. The "Great Chemical Bead Game" requires no instruments and presents the concepts of equilibrium and kinetics more clearly than an experiment. [October and November Computer Series both inadvertently called number 107. Numbering restored by skipping 109 and calling January 1990 number 110.]Cullen, John F., Jr. J. Chem. Educ.1989, 66, 1023.

Equilibrium |

Kinetics |

Rate Law

Solution equilibrium problems(Moss, David B.)Cass, Don; Murray, MarileeTwo reviews of a two disk set with a 44-page manual that discusses equilibria in general and specific techniques of solving equilibrium problems.Cass, Don; Murray, Marilee J. Chem. Educ.1988, 65, A114.

Equilibrium

The perils of carbonic acid and equilibrium constantsJencks, William P.; Altura, Rachel A.It is important to remember that the small amounts of carbon dioxide that are usually present in water can have large effects on acid-base equilibria of dilute solutions and that dilute solutions of most weak acids and bases undergo significant protonation or hydrolysis when they are dissolved in water.Jencks, William P.; Altura, Rachel A. J. Chem. Educ.1988, 65, 770.

Acids / Bases |

Equilibrium |

Aqueous Solution Chemistry

Tools of the trade Bruno, Michael J.High school teachers can never have too many visual aids when teaching chemistry. This author shares some demonstrations in equilibrium that often produce "oohs" and "aaaahs" from his students.Bruno, Michael J. J. Chem. Educ.1988, 65, 698.

VisiChemBreneman, G. L.70. Bits and pieces, 28. Many of the business spreadsheet programs can be used to answer "What if?" questions in chemistry due to the mathematical functions needed for science (such as logs, trig functions, square root) and others.Breneman, G. L. J. Chem. Educ.1986, 63, 321.

Le Châtelier's principle: the effect of temperature on the solubility of solids in liquidsBrice, L. K.The purpose of this article is to provide a rigorous but straightforward thermodynamic treatment of the temperature dependence of solubility of solids in liquids that is suitable for presentation at the undergraduate level. The present discussion may suggest how to approach the qualitative aspects of the subject for freshman.Brice, L. K. J. Chem. Educ.1983, 60, 387.

Strong and weak acids and basesDeck, Joseph C.The designations "strong" and "weak" are used in various ways, and often with respect to the same compound in different situations.Deck, Joseph C. J. Chem. Educ.1979, 56, 814.

Acids / Bases |

Equilibrium |

Aqueous Solution Chemistry

The temperature dependence of the equilibrium constantBurness, James H.This exam question tests a student's ability to derive the temperature dependence of an equilibrium constant not by qualitatively applying Le Chatelier's principle, but by understanding the relationship between the kinetics of the equation and the value of Keq.Burness, James H. J. Chem. Educ.1979, 56, 395.

Intuitive and general approach to acid-base equilibrium calculationsFelty, Wayne L.The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.Felty, Wayne L. J. Chem. Educ.1978, 55, 576.

Water dipping kinetics. A physical analog for chemical kineticsBirk, James P.; Gunter, S. KayPhysical analogs of zero-, first, and second-order kinetics using the volume of water transferred by a dipper oriented in different directions with respect to a basin of water.Birk, James P.; Gunter, S. Kay J. Chem. Educ.1977, 54, 557.

Molar solubility calculations and the control equilibriumChaston, S. H. H.The Control-Equilibrium method uses as its starting point a precise procedure for obtaining the equilibrium that accounts for the bulk of the decomposition of starting materials.Chaston, S. H. H. J. Chem. Educ.1975, 52, 206.

The design and use of an equilibrium machineAlden, Robert T.; Schmuckler, Joseph S.An operating model that can be used to determine quantitatively equilibrium shifts when demonstrating Le Chatelier's Principle and relates to molecular level considerations and the probabilistic nature of equilibrium.Alden, Robert T.; Schmuckler, Joseph S. J. Chem. Educ.1972, 49, 509.

The law of mass actionBerline, Steven; Bricker, ClarkIt is the purpose of this paper to present a derivation of the Law of Mass Action that should have meaning and could be used at an elementary level.Berline, Steven; Bricker, Clark J. Chem. Educ.1969, 46, 499.

Potentiometric measurements of equilibria: In general chemistry laboratoryChesick, J. P.; Patterson, Andrew, Jr.The authors describe an experiment in which the solubility product of silver chloride, the ionization constant of the silver-ammonia complex, and the ionization constant of acetic acid can be determined with one afternoon of work.Chesick, J. P.; Patterson, Andrew, Jr. J. Chem. Educ.1959, 36, 496.

Le Châtelier's principle and the equilibrium constantMiller, Arild J.Many students of chemistry have difficulty in understanding how the position of equilibrium in a gaseous reaction can change when the pressure is altered, in accordance with Le Châtelier's principle, without causing a corresponding variation in the equilibrium constant.Miller, Arild J. J. Chem. Educ.1954, 31, 455.

Equilibrium |

Reactions |

Gases

Praseodymium tetrafluoridePerros, Theodore P.; Munson, Thomas R.; Naeser, Charles R.In spite of the experimental failures to prepare praseodymium tetrafluoride, there is strong evidence for its possible formation to be found by calculating the equilibrium constants for some of the reactions by which this compound might be prepared.Perros, Theodore P.; Munson, Thomas R.; Naeser, Charles R. J. Chem. Educ.1953, 30, 402.